1. Field of the Invention
The present invention relates to a dry development device for reproduction machines and, more particularly, to a development of latent images of electrostatic charges formed on image supports that are held in contact with the magnetic brush by a plane guide surface.
2. Technical Consideration and Prior Art
Numerous dry development devices use powder development systems. An example of development devices using a magnetic brush to do this is described in U.S. Pat. No. 2,786,441.
In the direct electrostatic processes, i.e., processes in which the latent image of charges is formed directly on a final support, the following problem arises. The magnetic brush, which has been charged with powder, comes into direct contact with the guide surface, which causes the formation of a bead of powder between the magnetic brush and the guide surface. When, after formation of the latent image of charges, a sheet of paper is carried toward the magnetic brush, it engages under the brush by going through the bead. This forms black streaks on the back of the copy due to adherence of development powder.